diff --git a/rust-toolchain b/rust-toolchain
new file mode 100644
index 0000000..bf867e0
--- /dev/null
+++ b/rust-toolchain
@@ -0,0 +1 @@
+nightly
diff --git a/src/call.rs b/src/call.rs
index 8c19f0b..b3e7c45 100644
--- a/src/call.rs
+++ b/src/call.rs
@@ -349,3 +349,29 @@ pub fn write(fd: usize, buf: &[u8]) -> Result<usize> {
 pub fn sched_yield() -> Result<usize> {
     unsafe { syscall0(SYS_YIELD) }
 }
+
+/// If wifsignaled(status), the terminating signal.
+#[inline(always)]
+pub fn wtermsig(status: usize) -> usize {
+    status & 0x7f
+}
+/// True if status indicates normal termination.
+#[inline(always)]
+pub fn wifexited(status: usize) -> bool {
+    wtermsig(status) == 0
+}
+/// True if status indicates the child is stopped.
+#[inline(always)]
+pub fn wifstopped(status: usize) -> bool {
+    (status & 0xff) == 0x7f
+}
+/// True if status indicates the child continued after a stop.
+#[inline(always)]
+pub fn wifcontinued(status: usize) -> bool {
+    status == 0xffff
+}
+/// True if STATUS indicates termination by a signal.
+#[inline(always)]
+pub fn wifsignaled(status: usize) -> bool {
+    ((status & 0x7f) + 1) as i8 >= 2
+}